This document outlines the installation and configuration of the Database Availability Group on the mailbox server role. All this will take the installation and configuration to a total of minimum 2 servers in the overall DAG cluster. DAG is a new concept to the exchange application clustering on the database level. The new concept of the Database Availability Group (DAG) is exciting Exchange 2010 technology to bring low cost high availability without costly hardware SAN infrastructure. DAG takes less than 30 seconds in a failover. DAG can be expanded to multiple datacenters and up to 16 database copies.

Assumptions

This document assumes that:

Windows Server 2008 Enterprise x64 Edition is installed per baseline regulations which include the latest approved service pack and hotfixes.

Exchange 2010 Mailbox role servers are already installed on the same AD site.

2 NIC’s are configured per server one for replication of logs and other for production MAPI connectivity. The networks will be called Replication and MAPI in the document.

File Share Witness creation

File share witness guides the Hub Transport server which server has active database and ready to receive the emails. We need to create a folder on any one of the CAS/HT server.

Login to one of the HT/CAS server

Create a folder like C:\FSW_DAG1

Add “Exchange Trusted Subsystem group” in the local Administrators group.

Database Availability Group Creation

We can create DAG from Exchange management console and shell. We will do some part by the console rest by shell.

Give 1 IP address if both the nodes in the same subnet else give 2 IP addresses. Click ok and ok. IP has to be of the mapi network.

Manage Database Availability Group Membership

In EMC right click our DAG and select manage database availability group

On the manage database availability group page click the Add button

In the select mailbox server window select the both mailbox servers

Click ok then manage. In the screen there is only one server but we have to add 2 servers.

Selecting manage installs Windows clustering so it will take long time to finish

Click finish on the completion page

We can now see that both servers are added to the DAG. Something like below screen

Open active directory users and computersà go to computer OU. You will find computer object has created with the DAG name we supplied. This object will be used by windows clustering. Also check if the dns host record has created. It should be created automatically.

Open cluster admin then we will see the Windows clustering is installed.

Let open Windows Failover Clustering and see that the IP is assigned to the cluster.

Another item you will notice that is different from previous versions of Exchange is there are not clustered resources, no disks, not CMS/EVS.

The DAG only users Windows Clustering for heartbeat and quorum the new Active Manager is used to manage the DAG failover.

Configuring the networks

Go to the Exchange management console àOrganization configurationàMailboxàDAG Tab. Below you will see networks.

Select the Production network à go to properties and uncheck the checkbox “Enable Replication”.